Giuseppe Marco Tina

A radial basis function neural network based approach for the electrical characteristics estimation of a photovoltaic module

The design process of photovoltaic (PV) modules can be greatly enhanced by using advanced and accurate models in order to predict accurately their electrical output behavior. The main aim of this paper is to investigate the application of an advanced neural network based model of a module to improve the accuracy of the predicted output I–V and P–V curves and to keep in account the change of all the parameters at different operating conditions. Radial basis function neural networks (RBFNN) are here utilized to predict the output characteristic of a commercial PV module, by reading only the data of solar irradiation and temperature. A lot of available experimental data were used for the training of the RBFNN, and a backpropagation algorithm was employed. Simulation and experimental validation is reported.

Sentinella: Smart Monitoring of Photovoltaic Systems at Panel Level

The monitoring of photovoltaic (PV) systems is important for the optimization of their efficiency. In this paper, a low-cost smart multisensor architecture equipped with voltage, current, irradiance, temperature, and inertial sensors, for the monitoring (at the panel level) of a PV system, is presented with the aim of detecting the causes of efficiency losses. The system is based on a Wireless Sensor Networks with sensing nodes installed on each PV panel. The acquired data are then transferred to a service center where dedicated paradigms continuously perform the assessment of electrical efficiency as well the estimation of correlated causes, at the single panel level. In this paper, the detection of critical faults (temporary and permanent shadowing, dirtying, and anomalous aging) is addressed. The methodology adopted to estimate efficiency losses and related causes is based on the comparison between the measured efficiency of each PV panel and the nominal one estimated in the real operating conditions. Moreover, the anomalous aging estimation is based on the five parameter model approach that exploits a dedicated minimization paradigm to analyze the mismatch between the nominal current-voltage model of the PV panel and the measured one. The main advantage of the proposed approach is the continuous monitoring of PV plants and the assessment of possible causes of power inefficiency at the PV panel level, allowing for the implementation of a really efficient distributed fault diagnosis system. The experimental results are presented along with the analysis of the uncertainty affecting the measurement system.

Integration of multiple PV units in urban power distribution systems

Abstract The amount of power and energy that can be injected into the distribution system by dispersed generation (DG) is constrained by technical issues related to electrical components rating and distribution system operation. In this context, the aim of the paper is to study the voltage profile of a LV feeder in order to assess the maximum value of the power that can be injected into multiple load points of the feeder by PV units without violating the voltage constraints. To perform this study an analytical method with integral approach is used: the distribution of generators and loads along the feeder is represented by means of continuous functions and constant current model. The main result of the proposed study is that, with reference to a set of contiguous generation units, it is possible to derive analytical relationships between the position of the point of maximum/minimum voltage on the feeder and the characteristics of the distributed generation (e.g. length of the concerned feeder portion, position of the generators and overall current injected by the generators).

Study of the impact of PV generation on voltage profile in LV distribution networks

The present paper aims at assessing the effects produced on the distribution system by dispersed generators directly connected to LV networks. In particular, the introduction of photovoltaic (PV) generation systems has been studied, since such systems are the only ones having a natural inclination to be easily integrated into high density urban LV distribution networks. In the proposed study some aspects of the quality of power supplied to the customers will be dealt with taking into consideration slow voltage variations. In this regard the effect of dispersed generation (DG) on the voltage profile of a LV distribution feeder has been examined. With reference to a different kind of load distribution along the line, analytical expressions have been derived to determine the limit value of the power that can be injected into the distribution network without causing overvoltages. These expressions have been developed under some simplifying hypothesis related both to the DG unit and to the distribution network.

Electrical and thermal model for PV module temperature evaluation

In order to predict either the energy production of photovoltaic (PV) modules or to compare the performance of a real PV system against the optimal one, it is necessary to develop a suitable mathematical model that is able to calculate the PV cells layer temperature as a function of ambient temperature, wind speed, wind direction, total irradiance, and relative humidity. This paper presents an electrical-thermal model, also how the related parameters can be obtained and finally some experimental results concerning its utilization within a direct maximum power point (MPP) algorithm.

Field Experience With Performances Evaluation of a Single-Crystalline Photovoltaic Panel in an Underwater Environment

In this paper, the electrical and thermal performances of a single-crystalline submerged photovoltaic (PV) solar panel (SP2) is investigated. In particular, due to the presence of water, several phenomena occur such as the modification of solar-radiation spectrum and the reduction of the module operating temperature. These phenomena have different impacts on the global energy performance of the PV module, which depends on the environmental conditions, on the PV technology, and on the water depth. Energy performances of an SP2 module are measured using two different experimental setups in different environmental conditions, with an increase in power ranging from 10% to 15%.

Magnetic field evaluation for thick annular conductors

The three-dimensional integration of the Biot-Savart law for conductors in annular sector shape, in which only a constant-density theta -directed current flows, is reported. The expressions obtained allow a quick and accurate evaluation of the components of the vector potential of the stationary magnetic field and of the magnetic induction due to this type of conductor, in iron-free media. The relations presented, together with similar expressions that are valid for other shapes of conductor and current distributions, can be useful for evaluating the magnetic fields in complex, linear, iron-free structures when the geometry can be well approximated with a series of current elements of elementary shape, for which the solution of Laplaces equation is known in closed form. >

Analytic expressions for magnetic field from finite curved conductors

Some analytical expressions for the calculation of the magnetic induction and the vector potential in iron-free media due to conductors in annular arc shape with regular cross section are reported. The algorithms derived, together with analogous algorithms reported previously for the calculation of the magnetic fields due to conductors in slab shape, can be used to calculate the magnetic fields in more complicated geometries and may be used to evaluate the self- and the mutual-inductance coefficients in systems with massive conductors.

Comparison of different metaheuristic algorithms for parameter identification of photovoltaic cell/module

The estimation of the photovoltaic (PV) cell/module model parameters could lead to accomplish a diagnostic tool and to estimate several factors which affect the health state of a PV generator. In this context, it is crucial to look for an extraction technique which performs this evaluation precisely and quickly. Due to the nonlinear and implicit nature of the PV cell/module, significant computational effort is required to obtain all the parameters; therefore, in this context different metaheuristic algorithms are proposed. For the identification of the meaningful parameters of PV cell/module models, illuminated current-voltage (I–V) curves, under real conditions of PV cells temperature and incident irradiance, are employed. Considering several PV cell/module models, the goodness of the proposed algorithms is analyzed by means of statistical errors, convergence speed, and unknown parameters precision. Then these algorithms are tested and validated using a daily set of measured I–V curves, specifically for ...

Recurrent Neural Network-Based Modeling and Simulation of Lead-Acid Batteries Charge–Discharge

This paper presents the main experiences and results obtained about the problem of the lead-acid battery modeling and simulation. A nonlinear mathematical model is presented as well as results of neuroprocessing of the charge-discharge experimental and simulated data. Recurrent neural networks were used to provide a state-of-charge observer and model parameter estimation and tuning. The simulation results are compared with those obtained by extensive lab tests performed on different batteries used for electric vehicle and photovoltaic application.